POACEAE 
Stems simple, or sometimes sparingly branched at the nodes: 
eiie usually bright green: hairs on the leaf-sheaths re- 
exea: 
Spikelets 1.7-2 mm. long : leaf-blades usually pubescent, some- 
times nearly glabrous, commonly ciliate on the margins. 
Spikelets about 2.5 mm. long : leaf-blades glabrous, excepting 
/ sometimes a few hairs on the margin. 
Stems at length repeatedly dichotomous-branched, forming dense 
mats : plants grayish green : hairs on the leaf-sheaths, if any, 
ascending or appressed. 
Whole plant, excepting the spikelets, glabrous or nearly so, or 
the sheaths and blades sometimes pubescent. 
Spikelets broadly obovoid, about 2 mm. long. 
Spikelets obovoid, 2.5-3.5 mm. long. 
Ne lant, including the upper part of the stem, densely 
villous. 
b. Leaf-blades widely spreading. 
B. Leaf-blades of the main stem differing from the above, usually lanceolate 
to ovate-lanceolate, sometimes short and linear. 
Stems simple, or rarelya little branched at the lower nodes, forming 
dense tufts. 
Leaf-sheaths hirsute. 
Spikelets less than 1.5 mm. long. 
Spikelets exceeding 1.5 mm. long. 
Leaf-sheaths glabrous, excepting the ciliate margin; blades strongly 
and beautifully ciliate on the margins, otherwise glabrous. 
Spikelets about 1.5 mm. long, glabrous. 
yep 1.8-2 mm. long, pubescent. 
Stems finally branching at the upper nodes (sometimes remaining simple 
in number 89), often repeatedly branching. 
* Middle leaf-blades of the main stem less than 1.5 em. in width, usually 
less than 1 em. wide, the base rounded or truncate, sometimes in 
the broadest ones cordate. 
t Leaf-sheaths glabrous or puberulent, the lower ones sometimes 
with a few scattered long hairs, the margins often ciliate. 
Stem nearly naked above the base, a single leaf above the mid- 
dle of the stem. 
Stems leafy. 
Nodes barbed. 
Spikelets glabrous : 
A little less than 2 mm. long. 
About 2.5 mm. long. 
Spikelets pubescent. 
Nodes naked. 
Spikelets glabrous. 
Spikelets less than 1.5 mm. long. 
Stems densely tufted, less than 3 dm. tall, finally 
much-branched and prostrate and forming large 
mats: spikelets about 1 mm. long. 
Stems exceeding 6 dm. tall: spikelets about 1.3 mm. 
long. 
Spikelets 1.5-2 mm. long. 
Leaf-blades ciliate with long hairs, at least for the 
Jower half. 
Leaf-blades not ciliate. 
Primary leaí-blades of the stem large, 9-12 cm. 
ong. 
Primary leaf-blades of the stem small, rarely ex- 
ceeding 6 em. long. 
Leaf-blades widely spreading, thin. 
Stems remaining erect, branching at the mid- 
dle, the late state assuming the form of 
a little tree. 
Stems becoming prostrate, branching their 
whole length. 
Leaf-blades erect: 
Thin : stems finally much-branched and pros- 
trate. 
Ligule membranous, 0.25 mm. long to al- 
most wanting: spikelets elliptic. 
Ligule of erect hairs about 1 mm. long: 
spikelets obovoid. 
Firm, the basal ones thick and much broader 
than the upper. 
Spikelets 2.5-3 mm. long: 
Elliptic : stems finally much-branched and prostrate. 
Broadly obovoid : stems erect. 
Spikelets pubescent. 
2 Spikelets less than 2 mm. long. : 
Leaf-blades ciliate for at least 14 their length. 
Panicle ovoid: spikelets few, 1.75 mm. long: leaf- 
blades small. 
Panicle oblong : spikelets numerous, 1.3 mm. long: 
leaf-blades large. ; : 
Leaf-blades naked on the margins, or sometimes with 
a few long hairs at the very base. 
46. 
45. 
47. 
48. 
49, 
107. 
52. 
87 
P. laxiflorum. 
P. pyriforme. 
P. neuranthum. 
P. angustifolium. 
P. consanguineum. 
P. equilaterale. 
. P. strigosum. 
. P. laxiflorum.. 
. P. polycaulon. 
. P. ciliatum. 
. P. nudicaule. 
. P. barbulatum. 
. P. nemopanthum. 
. P. Mattamuskeetense. 
. P. Baldwinii. 
78. 
P. octonodum. 
P. Nashianum. 
. P. Yadkinense. 
. P. dichotomum. 
. P. lucidum. 
. P. lucidum. 
. P. curtivaginum. 
. P. Roanokense. 
P. sphagnicola, 
P. pernervosum. 
. P. Nashianum. 
91. P. erectifolium. 
